1. Field of the Invention
This invention relates to a woven diaphragm for aqueous electrolytes, such as alkali metal chloride solutions, hydrochloric acid solutions, and sulfuric acid solutions and for the electrolysis of water to which acids and/or alkalis have been added.
2. Description of the Prior Art
The technique of electrolysis by the diaphragm process is described in the relevant literature, cf. the article by Hund and Minz in Winnacker-Kuchler "Chemische Technologie", Vol. 2. "Anorganische Technologie I", page 379 (1982), more particularly page 392, pages 404 et seq and pages 442 et seq.
Hitherto, the diaphragms used for the electrolysis of alkali metal chlorides have been, in particular random-fiber mats of asbestos fibers. The need to replace asbestos as far as possible has produced proposals to use fluorocarbon polymers for diaphragms in the form of woven fabrics or films, optionally incorporating inorganic fibers.
Hitherto, woven PVC cloths in particular have been used in the diaphragm process for the electrolysis of hydrochloric acid.
Woven fabrics of polytetrafluoroethylene fibers which have been hydrophilized by treatment with an acid and/or by irradiation have been proposed for the electrolysis of water.
An ideal diaphragm has to satisfy a number of in some cases conflicting, requirements, such as resistance to the electrolytes and the reaction products, adequate porosity for passage of the electrolyte, a good separation effect for the reaction products and also a low ohmic resistance.
Now, the present invention provides diaphragms which are distinguished in particular by the weave thereof.